1) Field of the Invention
The field of this invention relates to pipe fittings and more particularly to an interconnecting male coupler and female coupler which are to be connected together in a liquid tight manner between a pair of pipe sections which are slightly axially spaced apart.
2) Description of the Prior Art
The use of pipe fittings for connecting together a pair of axially spaced apart pipe sections has long been known. In the laying of any liquid conducting pipe, generally the pipe sections come in prescribed lengths, such as twenty feet in length or any other custom required length. When laying of a length of pipe greater or lesser than standard available length, there is therefore required pipe fittings to connect together the joined pipe sections in a liquid tight manner. Normally, for reasons of economics, plastic pipe is being used with greater frequency as opposed to metallic pipe. Plastic pipe has the advantage that it does not rust as does metallic pipe. However, plastic pipe also has the disadvantage in that it is not as strong as metallic pipe and especially in the area of the fittings that interconnect the different sections of pipe, it is difficult to apply a sufficient amount of compressive force in connecting together of the couplers of the fitting in order to achieve a long lasting liquid tight connection.
In the past, in order to design a stronger plastic fitting or coupling, it has been common to incorporate one or more metallic members within the fitting that are to be used to establish a high degree of compression in forming of the fitting. Plastic fittings alone have been proved incapable of being torqued sufficiently to produce a leak proof fitting for a long period of time owing to its lesser strength compared to metals. Even after the incorporation of the metallic member, the fundamental problem of a liquid leak proof joint remained to be solved due to the formation of a gap at the surface of metal and plastic interface due to inherent property of plastic to shrink after injection molding. Sometimes this gap formation also occurs during over tightening of the fitting resulting in exterior leaks over a period of time. Inserting bigger sizes of metallic inserts and threading the entire length of metallic inserts, exteriorly or interiorly also adds to the cost which is finally to be borne by end users. Some of these prior art types of fittings require the use of several different parts which requires an assembly procedure of the fitting prior to interconnecting of the male coupler and female coupler of the fitting.
If the fitting is constructed totally of plastic, it has been discovered that a totally plastic male coupler and female coupler, when engaged, cannot be tightened sufficiently due to their inherent lesser compression strength than metal fittings to establish sufficient compression that will produce a long lasting liquid tight relationship between a pair of pipe sections.